Flow : The Psychology of Optimal Experience by Mihaly Csikszentmihalyi This book is essential for any interaction or experience designers. Any program I write aims to include or enhance this effect.

The Design of Everyday Things by Donald A. Norman His opinions on affordance and design greatly influenced me when I first started interaction design.

NTSC video:Powers of Ten by Charles & Ray Eames NTSC video of the classic Powers of Ten book - and if you want the book by Philip& Phylis Morrison  or the Charles & Ray Eames Flipbook

Palm Programming : The Developer's Guide by Neil Rhodes, Julie McKeehan This is the book I use to explore  aspects of programming the Palm Pilot. Good reference and well written.

Palm Pilot Programming : Create Custom Applications for All Palm OS Devices by Glenn Bachmann Although not available yet, this looks interesting.

Teach Yourself Palm Programming in 24 Hours With CDROM by Gavin Maxwell, Brad Jones Quite a simple and easy introduction to Palm Pilot programming.

The Art of Electronics  by Paul Horowitz, Winfield Hill Although a heavy tome, this book is an excellent reference for electronic circuits, ignore the equations and use the diagrams.

The Forrest Mims Engineer's Notebook by Forrest M. Mims, Harry L. Helms The above is the compilation book by Forrest Mims, I prefer the smaller engineer's notebook's only available from your local Radio Shack store.

Robots, Androids and Animatrons : 12 Incredible Projects You Can Build by John Iovine This book is a treasure trove of information about sensors and controlling motors.